DIN EN ISO 2931:2010-12

This standard specifies a method for assessing the quality of sealed anodic oxidation coatings on aluminium and its alloys by measurement of the admittance. The method is applicable to anodic oxidation coatings sealed in an aqueous solution. The method is suitable for use as a productions control test and as an acceptance test where there is agreement between the manufacturer and the purchaser. Any type of anodized component may be tested by the method described, provided that there is sufficient measuring area (a circle of about 20 mm diameter) and the film thickness is greater than 3 µm. Principle: an anodic oxide coating on aluminium may be represented as an electrical diagram made up of a certain number of ohmic and capacitative resistances mounted in series and/or parallel in an alternating current circuit. The numerical value of these resistances depends on the following variables: - basis metal (for example, composition, size and distribution of intermetallic compounds, and surface condition) - sealing process (for example steam, hot water, nickel or cobalt salts; or cold sealing) - thickness and density of anodic oxide layer (for example depending upon electrolyte, type of current, current density, electrolyte temperature) - dying and pigmentation processes used to colour the anodic oxide coating - time and conditions of storage between sealing and measurement. The International Standard has been prepared under the leadership of ISO/TC 79/SC 2/WG 16 "Revisions for systematic reviewed TC 79/SC 2 ISO standards" (secretariat: JISC, Japan) in a parallel procedure with CEN/TC 132/WG 15 "Aluminium anodisation" (secretariat: BSI, United Kingdom). On the national level the responsible Working Committee is NA 066-01-09 AA "Anodisch oxidiertes Aluminium" ("Aluminium anodisation") of FNNE.